The invention relates to motor car structures.
Racing cars and other high performance light-weight motor cars which may be sports-racing cars or road going sports cars incorporate a basic vehicle structural element or chassis which is normally referred to as a tub. The tub normally incorporates a floor, sides, front and rear bulkheads and possibly extensions of some of these elements to carry engines, suspensions, transmissions or other essential parts of the vehicle. In some cases, the tub may also incorporate a roof in which case the sides have to be relatively low to permit driver access.
One established material for manufacture of a tub is aluminium or other light metal sandwich structure. Sandwich material incorporates two skins united by a core of expanded material. One popular sandwich material is known as honeycomb material and has a core constituted by a hexagonal matrix of a material which may be the same as or different from that of the skins. The established procedure for joining together flat sandwich panels to form a tub is by means of angle section strip material bonded and rivetted to at least one skin of each of the panels being joined.
Joins of this kind add weight to the structure, can result in weak points in the structure, are time consuming to assemble and require accurate positioning of rivet holes in the panels and strips.
A more recent development has been to build tubs with a sandwich structure by laying one skin of fibre-resin composite material on a former, applying a sandwich core to the first skin and subsequently laying a second composite skin over the core. With a suitable former, the floor, sides, bulkheads and other parts of the tub can be formed integrally, thus reducing or even avoiding the requirement for joints between individual panels.
Manufacture of a tub in this way is very labour intensive and the cost can amount to several times that of a corresponding tub manufactured from flat sandwich panels joined together.